Self-regulating alternating current generator with self-excited exciter



Nov. 10, 1953 RON A 2,659,045

SELF-REGULATING ALTERNATING CURRENT GENERATOR WITH SELF-EXCITED EXCITER Filed Nov. 25, 1952 2 Sheets-Sheet 1 INVENTOP Em\\ R Nov. 10. 1953 E. RONA 2,659,045 SELF-REGULATING ALTERNATING C ENT GENERATOR WITH SELF-EXCITED E TER Filed Nov. 25, 1952 2 Sheets-Sheet 2 IIVMEA/I'OP E Ron a Patented Nov. 10, 1953 SELF-REGULA'I'IN G ALTERNATING CUR- RENT GENERATOR WITH SELF-EXCITED EXCITER Emil Rona, Ingolstadt, Germany 7 Application November 25, 1952, Serial No. 322,416

Claims priority, application Germany November 26, 1951 8 Claims.

This invention relates to a self-regulating alternating current generator with self-excited exciter which is compounded in the armature and provided with empty i. e. non-wound poles.

Alternating current generators with rotary frame and an additional armature winding traversed by the load current of the generator, with self-excitation, taking the no-load excitation from its own collector rather than from a separate source of current or a separate direct current winding disposed in the armature of the generator, require exciters compounded in the armature whose pole system is constructed to exhibit to a very great extent the features of the so-called Ewings method, so as to maintain the stability. The consequences thereof, however, are a higher amount of copper required in the exciter winding, reduction of the efiiciency and higher inertia. Moreover, these machines are capable of carrying capacitive load only to an extent depending on the ratio of the no-load excitation to the armature reaction.

It is an object of the present invention to provide an arrangement by which these drawbacks can be largely avoided.

More particularly, it is an object of the inven tion to reduce the amount of copper required for the windings, to reduce the losses and the inertia and to improve the stability.

Still another object is to provide a generator of the kind referred to supplying a very constant no-load voltage.

A still further object of the invention is to provide a variable additional excitation.

Other and further objects, features and advantages of the invention will be pointed out hereinafter and appear in the appended claims forming part of the application.

In the accompanying drawings several now preferred embodiments of the invention are shown by way of illustration and not by way of limitation.

- Fig. 1 is a diagrammatic sectional view showing a four-pole exciter having the invention applied thereto,

Fig. 2 is a diagram of connection therefor,

Fig. 3 is a diagram showing the potentials of the commutator,

Fig. 4 is a diagrammatic sectional view showing a modified form of exciter and Fig. 5 is a modified diagram of connection.

Similar reference numerals denote similar parts in the difierent views.

Referringrnow to the drawings in greater detail, and first to Fig. 1, it will be seen that the exciter shown in this figure is a four-pole eX- citer having only two successive poles P1, P2 carrying the winding W1, while the remaining poles P3 and P4. are non-wound or empty. As shown in Fig. 2, the armature 4 of the generator and the armature 5 of the exciter are mounted on the same shaft diagrammatically indicated by the center line 6, as known per se, and have the same number of poles. The armature 5 of the exciter comprises a direct current winding W2 in the form of a lap winding without equalizing or equipotential connection, leading to the collector, and a three phase current additional winding We of which only one phase is shown in Fig. 2.

The conventional parallel connections of the homopolar brushes b1, b2, b3, 214 are omitted. The pair of brushes b1, b2, called no-load brushes, feeds the exciter windings W1 and W4, while the pair of brushes b3, b4, called load brushes, feeds the winding W5.

During noload run of the generator the noload field c of the exciter corresponding to the no-load field 0f the generator is used, which field is excited by the winding W1 and closed through the poles P1 and P2. The voltage generated in all armature conductors of the direct current winding produces a potential curve of the commutator corresponding approximately to the curve I of Fig. 3, with the highest voltage between b1 and b2 and zero voltage between in and 224. Accordingly the winding W5 is dead on noload. The poles carrying a winding are dimensioned in such a way that already by the field a full saturation is existing therein which saturation with a view to the stability especially in case of capacitive load is as high as possible, and that the voltage on the brushes b1, in under load owing to the effect of the armature portion of the winding W3 cannot rise any more by an amount which is higher than that produced by the change of the leakage flux between the pole tips and the teeth of the armature.

When the generator is operating under load, all poles of the exciter are additionally uniformly excited by the ampere conductors of the winding W3. Supposing, for instance, that the current is strictly lagging wattless current, i. e., cos p=0, the armature windings of We will substantially uniformly add to the flux due to the winding W1.

Owing to saturation the field cannot be increased any more in the poles P1, P2, but in the poles P3, P4 the additional field will be built up without hindrance, whereby the potential drop is displaced in accordance with the curve 2 of Fig. 3 owing to the voltage induced in the armature conductors.

The voltage thus resulting on the load brushes b3, b4 is used for producing the additional excit ing current in the winding W5, so that it is possible to adjust automatic voltage regulation under load by means of a regulator.

In case of capacitive load the field in the poles P1, P2 is weakened by the armature winding of W3, the field is reversed and the voltage at the load brushes b3, b4 is reversed as per curve 3 in Fig. 3. The winding W operates in an opposite direction of W4, thus producing the weakening of the field required in the generator. By a high initial excess of the excitation W1 over We, i. e., a very high saturation on no-load, reduction of the field 5,, to zero can be avoided.

An even better way of ensuring the stability of the voltage in case of capacitive load, which is very important for parallel operation with the mains or with other generators can be obtained in accordance with Fig. 5 by feeding from the brushes b1, b: or b2, In an additional winding We provided on the poles P1 and P2 as a compensating winding. This winding may also be divided in two halves, one of which is connected to b1, b3, while the other one is connected to bi, bi. The effect will be clear from the three curves of the potential diagram of Fig. 3, i. e., the voltage at the brushes b1, b3 rises from no-load to full load in case of capacitive current and increases the excitation in the poles P1, P2, whereas in case of inductive current it is decreased and weakens said excitation. The reaction of the armature winding W3 upon the poles P1, P2 can be compensated by an adjustable regulator in the circuit We, thus maintaining the condition of saturation. In this case, the full increase or decrease of regulating output in case of load has to be covered by the remaining poles alone.

The same effect can be obtained by feeding the winding We from the load brushes b3, b4, if the connection is made in such a way that its effect in case of inductive current is opposed to that of W1.

In the course of one period the armature conductors are active by producing no-load current and additional current, thus achieving a compensation in case of difierent load.

Instead of exciting two poles, as hereinbefore described, it is also contemplated, within the purview of the present invention to excite only one pole with a similar effect; in this case, again the no-load excitation is taken from the brushes of highest voltage and the additional excitation is taken from the brushes with zero voltage on no-load.

Further it is contemplated within the purview of the present invention to provide an exciter with poles of different width and with non-uniform distances between the brushes, for instance, as shown in Fig. 4. It will be appreciated that it is thus possible to adapt the division of the periphery of the armature in a better way to the required amounts of no-load and additional exciter output.

In case of four-pole exciters two poles or three poles or four poles or a part of the total number of poles adapted to the regulating ratio may be provided with a winding; again, brushes having the same potential may be connected to each other.

It will be understood that by the construction as hereinbefore described with partly empty poles and a single collector the amount of copper for the windings and the losses are reduced and a higher stability and lower inertia can be achieved, and the tasks of (1) Supplying a very constant no-load voltage and (2) Providing a variable additional excitation can be met fully.

Moreover, the generator owing to its constant voltage can be used for other purposes, such as, battery charging.

While the invention has been described in detail with respect to certain now preferred examples and embodiments of the invention it will be understood by those skilled in the art after understanding the invention that various changes and modifications may be made without departing from the spirit and scope of the invention and it is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed is:

1. An alternating current generator comprising more than two poles, subdivided exciting windings and an exciter whose armature winding is additionally traversed by the load current of the generator, said exciter having more than two poles of which not more than two successive poles are wound while the rest of the poles are not wound, two successive no-load brushes associated to the wound poles and supplying the no-load current for the generator and the exciter, and load brushes supplying the additional exciting current for operation under load.

2. An alternating current generator comprising more than two poles, subdivided exciting windings and an exciter whose armature winding is additionally directly traversed by the load current of the generator, said exciter having more than two poles of which not more than two successive poles are wound while the rest of the poles are not wound, two successive no-load brushes associated to the wound poles and supplying the no-load current for the generator and the exciter, and load brushes supplying the addi tional exciting current for operation under load.

3. An alternating current generator comprising more than two poles, subdivided exciting windings and an exciter whose armature winding is additionally indirectly traversed by the load current of the generator, said exciter having more than two poles of which not more than two successive poles are wound while the rest of the poles are not wound, two successive no-load brushes associated to the wound poles and supplying the no-load current for the generator and the exciter, and load brushes supplying the additional exciting current for operation under load.

4. An alternating current generator comprising more than two poles, subdivided exciting windings and an exciter whose armature winding is additionally traversed by the load current of the generator, said exciter having more than two poles of which not more than two successive poles are wound while the rest of the poles are not wound, two successive no-load brushes associated to the wound poles and supplying the noload current for the generator and the exciter, and load brushes supplying the additional exciting current for operation under load, the wound poles being provided with an additional winding supplied from the load brushes, for compensating the armature reaction due to load current.

5. An alternating current generator comprising more than two poles, subdivided exciting windings and an exciter whose armature winding is additionally traversed by the load current of the generator, said exciter having more than two poles of which not more than two successive poles are wound while the rest of the poles are not wound, two successive no-load brushes associated to the wound poles and supp-lying the no-load current for the generator and the exciter, and load brushes supplying the additional exciting current for operation under load, the wound poles being provided with an additional winding supplied from one no-load brush and one load brush, for compensating the armature reaction due to load current.

6. An alternating current generator comprising more than two poles, subdivided exciting windings and an exciter whose armature winding is additionally traversed by the load current of the generator, said exciter having more than two poles of which only one is wound while the rest of the poles are not wound, no-load brush means associated to the wound pole and supplying the no-load current for the generator and the exciter, and load brushes supplying the additional exciting current for operation under load.

7. An alternating current generator comprising more than two poles, subdivided exciting windings and an exciter whose armature winding is additionally traversed by the load current of the generator, said exciter having more than two poles of which only a part is wound while the rest of the poles are not wound, n-o-load brush means associated to the wound poles and supplying the no-load current for the generator and the exciter, and load brushes supplying the additional exciting current for operation under load.

8. An alternating current generator comprising more than two poles, subdivided exciting windings and an exciter whose armature winding is additionally traversed by the load current of the generator, said exoiter having more than two poles of which not more than two successive poles are wound while the rest of the poles are not wound, two successive no-load brushes associated to the wound poles and supplying the noload current for the generator and the exciter, and load brushes supplying the additional exciting current for operation under load, the wound poles being different from the non-wound poles as to their cross section and the circular distance of the poles and brushes being different.

EMIL RONA.

No references cited. 

